The reason why angled spacers have been introduced in some cases is that with conventional implant systems the securing screw for the tooth bridge can sometimes end up in an unsuitable position. By means of an angled spacer, the securing screw can be placed in a position which is more favorable from the point of view of appearance and from the point of view of dental technique.
Many of the previously known angled spacers are also adjustable, although in many cases this is a disadvantage since it is difficult to recover the exact position if the setting becomes loose. and to get a tooth bridge into place if the setting has been dislodged. In addition, certain constructions of this type are weak and offer poor resistance due to the fact that they have been made up of a ball with a narrow neck. Another disadvantage of these previously known constructions has been that pockets exist in which bacteria can gather and give rise to inflammations.
Angled spacers with a fixed angle between the fixture and the prosthetic attachment screw are also already known, for example, from EP 0 323 421. In this patent the spacing member is designed as a single part and has a conical base portion which can be securely locked in a defined direction of deflection in relation to the fixture by means of a first screw connection, a segment-shaped intermediate part, and a conical upper part with a second screw connection for attachment of the tooth prosthesis, the second screw connection forming a fixed angle, preferably within the range of 25.degree.-40.degree., in relation to the first screw connection. An angled spacer of this type is strong, comprises few parts and makes it easy for the prosthodontist to recover the correct position should the setting come loose. However, in their present form, the angled spacers with a fixed angle also have certain limitations. These limitations are that the angle is too great in many clinical cases. The existing angled spacer may have an angle of about 30.degree., whereas a more desirable angle would be about 15.degree.. To achieve this using today's basic solution, the upper conical attachment part must be made very much higher in order to provide room for the internal thread in the upper conical part. Such an increase in height is not desirable, since this would severely limit the usability of the component. Other conceivable solutions, such as, for example, an asymmetrically positioned hole in the upper conical attachment part, may be possible, but these have the result that a number of components then also become asymmetrical and are thereby difficult to manufacture and to use without losing the precision in the subsequent laboratory work.
Another limitation of existing angled spacers is that the spacer height is too great to permit a satisfactory aesthetic appearance in a relatively large number of cases. This problem can be solved by reducing the angle. However, the screw head on the screw which secures the spacer to the fixture then gets in the way of the conical cap which is secured over the spacer.